Apparatus for making fine fibers



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APPARATUS FOR MAKING FINE FIBERS Filed Oct. 20, 1944 3 Sheets-Sheet 3 IN V EN TOR.

4/0n M! Hansen BY JTTOR/VEKS Patented Mar. 18, 1947 UNITED STATES PATENT OFFICE APPARATUS FOR MAKING FINE FIBERS Alden W. Hanson, Midland, Mich., asslgnor to The Dow Chemical Company, Midland, Mich., a corporation of Michigan Application October 20, 1944, Serial No. 559,612

(Cl. Iii-2.4)

6 Claims. 1 This invention relates to a machine for making fine fibers, especially from materials capable of formingsuch fibers at or near room temperature. It relates in particular to certain novel features and combinations of features of a machine fdr the purpose stated.

A principal object is to provide a machine for drawing a multiplicity of fine fibers from a fiberforming material in a liquid or semi-liquid state without the use of the usual orifice, die or spinneret means to impart the fiber shape to the material.

, A particular object is to provide a machine for drawing simultaneously to average diameters under 3 microns alarge number of fine organic fibers.

Further objects include the provision of a machine for the purpose stated having fiber generating means comprising two or more coacting rollers and correspondingly one or more fiber harvesting points, driving means for the various elements, and two or more of the following features: (a) means for distributing uniformly to the fiber generating surfaces a supply of fiberforming liquid; (22) means. for harvesting continuously the generated fibers: and means for forming webs or batts of the accumulated fibers.

Other and related objects will become apparent from the following description and the related annexed drawings wherein,

Fig. 1 is a side elevation of the machine, in partial section, showing a plurality of coacting fiber-generating rollers, a plurality of harvesting points, one type of harvesting means, a means for supplying and another for distributing uniformly a fiber-forming liquid, and appropriate drives for the machine;

Fig. 2 is an elevation of the opposite side of the machine showing principally two styles of the batt-reeling means of Fig. 3 and an exhaust system for solvent vapor;

Fig. 3 is an end elevation of the embodiment shown in Figs. 1 and 2, together with one form of batt producing means;

Fig. 4 is a view in vertical section through a plurality of fiber-generating rollers and associated flexible metal tapes to harvest the fibers, showing also, in elevation, a preferred means for supplying and distributing the fiber-forming liquid; and,

Fig. 5 is a view taken along line 5-5 in Fig. 4.

Throughout Figs. 1-5, like numerals refer to like parts.

The machine illustrated in the drawings is one capable of producing fine fibers by a method which is described in my copending application Serial No. 460,741, filed October 5, 1942, and in a continuation-in-part thereof, Serial No. 554,210, filed September 15, 1944, now U. S. Patent No. 2,385,358. That method comprises continuously supplying to and conveying through an elongated pressure zone a liquid fiber-forming composition capable of adhering to opposed rotary pressure members defining said zone, releasing the pressure on said liquid to produce a multiplicity of opposed pairs of fiber necks on said opposed rotary pressure members, each of said pairs connected by a single filament, drawing fibers from said necks by moving pairs thereof along divergent arcuate paths, and collecting the fibers while continuing the drawing thereof.

The machine of the present invention comprises a pair (or more) of horizontally disposed rollers in face-to-face relation, tension means to form a pressure zone between said rollers, means for distributing a substantially uniform thin film of fiber-forming liquid across the face of the rollers, driving means operative to rotate adjacent rollers in opposite directions to convey a film oi fiber-forming liquid therebetween and to generate and draw out fibers between points on the paired receding arcuate surfaces, and means for harvesting the fibers.

In the illustrated embodiment of the invention, reference being had to Figs. 1, 2 and 3, a plurality of smooth-faced cylindrical steel rollers 10 are supported on a master framework 9 in a horizontal plane with their axles I I parallel and initially spaced apart a distance barely greater than the diameter of the rollers l0. As a driving means, a motor l2, connected through reduction gear l3 to shaft l4, drives shaft 11 by means of chain i8 which passes around sprockets i5 and I9, as shown. On shaft I! are mounted pinions 20 disposed so as to engage bevel gears 2i mounted on axles H of rollers I 0 and to turn successive rollers ill in opposite directions. Mounted above rollers ill is a feed header 22 which receives fiberforming liquid through flexible tubes 23 and 24 from a source, not shown, and supplies that liquid to the rollers through tubes 25 and 26. Header 22 is mounted transversely of rollers l0 and is movable longitudinally thereof, being carried on casters 21 which roll on tracks 28, and actuated by the self-reversing shuttle mechanism consisting of endless chain 29, passing around sprockets 32 and 33, having on one link thereof a laterally extending lug 30 cooperative with slotted arm 8! dependent from header 22. Sprocket 33 on shaft 3 34 is driven by motor 33 through chains 35 and 33 passing over and around a train of sprockets 35 and 40-43, inclusive, as shown. As chain 28 moves along the upper half of its path between sprockets 32 and 33, lug 30 engages the upper end of arm'3l and causes header 22 to roll along track 28 toward sprocket 33. As lug 30 on chain 29 passes sprocket 33 and starts its return to sprocket 32 along the lower half of its course, it engages the lower end of arm 3| and pushes header 22 back along track 28 toward sprocket 32. Sprocket 43 is mounted on shaft 31 above rollers III, while sprocket 42 is similarly mounted on shaft 44 disposed beneath the said rollers. both shafts 31 and 44 being driven at the same speed.

Shafts 31 and 44 serve to drive the fiber harvesting mechanism. Thus, there are mounted on these shafts at intervals along their lengths, near the harvesting points on the neighboring rollers l0, sprockets 45 and 45 which are connected, respectively, by chains 41 and 48 to sprockets 49 and 50 mounted, in turn, on shafts and 52. These latter shafts are located beyond the end of and transversely to the fiber-forming area ofcoacting rollers Ill, and carry pairs of sprockets 53 spaced apart a distance somewhat less than the diameter of each roller Ill, centered above or beneath the fiber-forming areas of the pairs of said rollers. Sprockets 53 carry endless chains 54, which run parallel to one another and to rollers i0, passing over idler sprockets 55 mounted on transverse shafts 56 beyond the end of rollers i0 away from shafts 5| and 52. Shaft 56 drives harvesting reels 51 mounted on shafts 58, by means of sprockets 59 and 60 and chain 6|.

Fiber-forming liquid, deposited on the upper surfaces of rollers it by tubes 25 and 26, is distributed in a uniform thin film over those surfaces by scraper or doctor blades 62, held against the rollers Ill by adjustable pressure applied to shaft 63 by means of spring 64. Any accumulation of fiber-forming liquid above scraper 62 is confined within the elongated zone between the adjoining rollers Ill by means of endplates 65 fastened to the ends of scraper 62 and fitting snugly against the ends of rollers H).

An alternate means of applying the fiber-forming liquid to rollers i0 is shown in Figs. 4 and 5. Rollers I0 are mounted as before on axles ll driven through bevel gears 2| by pinions (not shown) mounted on shaftl'l'which, in turn is driven as in Figs. 1 and 3. On shaft I, internally of bevel gear 2|, is mountedsprocket I0. Scraper blades 69 serve to keep fiber-forming liquid from flowing over and drying on the ends of rollers i0. Above rollers l0, and disposed transversely there- .to, is a framework to support individual feed boxes II for applying fiber-forming liquid to rollers it. This framework may consist of channel irons l2 dependent from hanger 13 which houses casters l4, movable along monorail 15 disposed longitudinally of rollers In. Feed boxes H, which may be filled with fiber-forming liquid from tubes 23 and 24 by suitable opening of the valves shown thereon, are suspended by means of lever arms 16 from framework 12 and are held snugly against rollers l0 as by springs ll. Motionof feed-boxes 1| longitudinally of rollers ill is'effected by means of a self-reversing "level-wind mechanism consisting of a double-helically grooved rotary shaft 18 supported near its ends on the master framework 9 of the machine in bearings (not shown), and cooperative with a follower bracket 19 mounted on feeder framework 12. Shaft I8 is driven by chain 44 passing around sprockets I0 and 3|. Close contact is maintained between adjacent rollers III by means of springs 65 mounted on the master framework 3 of the machine, operative on the bearings around axles H of the outside or end rollers of the machine to force the rollers together toward the center of the tier. Similar results may, of course, be obtained with other tension means. i

, Referring to Figs. 2 and 3, harvesting reel 51. driven to rotate about a horizontal axle 54, and of a width barely to permit insertion between the rims of paired sprockets 55, is driven as aforesaid by chain 6| which passes over and around sprockets 59 and 60. as shown in Fig. 3. The cylindrical surface of reel 51 is suitably formed of coarse wire screen 61, one-half inch mess being satisfactory. An exhaust system, to remove some of the solvent vapor from the freshly formed fibers may be provided, and may suitably consist of a sheet metal ductwork 68 opening into the center of reels 5! around one terminus of axis 58 thereof, and connecting with a suction means, not shown. The above-described cylindrical reel may be replaced by a pair of disks 84 mounted in the positions occupied by the ends of reel 51, thus forming the ends of an imaginary right cylinder, and serving to collect fibers from the primary harvesting means, as is shown in the upper lefthand portion of Fig. 2 in the accompanying drawing.

Certain mechanical equivalents or modifications of features of the machine may, of course, be substituted for the embodiments shown in the drawings. Thus, belt or other mechanical drives may be substituted for the numerous chain and sprocket drives without departing from the scope of the invention. In addition, the fiber-forming liquid may be fed to the rollers by an applicator roll, instead of the means herein described. Likewise, harvesting of the fibers may be accomplished by a belt instead of by parallel chains 54. More advantageously, chains 54 may be replaced by endless, flexible steel tapes 85 (Fig. 4), in which case sprockets 53 and 55 will be replaced by wheels having guards or suitably profiled rims to keep the tapes in alignment. In any case, it may prove desirable to provide a. cleaning mechanism of any appropriate design at some point along the idle section of the path traversed by chains 54 (or equivalent belt or tapes) to remove at least periodically any accumulation of fiber ends adhering to the primary harvesting device.

In operation of the herein described machine to produce fine fibers, motor i2 is started, and sets in motion rollers l0. Fiber-forming liquid is released into header 22 or feed boxes II mary harvesting means (chains 54 or equivalent) and the secondary harvesting reel 51, or other fiber accumulator. As rollers become coated with viscid fiber-forming liquid, either directly from feed boxes H or travelling tubes 25 1and .26, or by transfer of liquid from contiguous rollers, the film of liquid is first compressed in. the nip between adjoining rollers and then is split and divided between portions adhering to each of the rotor faces as those faces recede. during revolution, from the nip. The liquid on each rotor face few minutes.

is pulled out and necks and as the motion of the rotors continues, pairs of such liquid pools or necks on opposing roller faces, connected by a single filament.- are stretched apart, lengthening the' filament and spinning it into a fine fiber. The large number of such fibers formed at any given instant gives the appearance of a network of'more or less parallel fibers extending between the receding rotor faces, as indicated in the drawings by lines 82. As the fibers are thus being drawn they are hardened or set, usually by evaporation of volatile solvent.

Continued motion of rollers l carries fibers 82 to the moving harvester chain 54 to which they adhere, severing them from the rotor surfaces. Chain 54 carries them in turn to an accumulator, such as reel 51 which picks the fibers from the chain. Rotation of reel 51 results in the accumulation thereon of a fibrous web or batt 83 of considerable thickness in the course ofa Such batt may periodically be stripped from reel 51 and, after further drying, is ready for use in industrial processes, in applications where fine fibers are desired.

The process of making fibers, as outlined briefiy above, is more fully set forth in my aforesaid copending applications, Serial No. 460,741, filed October 5, 1942, and Serial No. 554,210, filed September 15, 1944, now U. S. Patent No. 2,385,- 358.

As an example of the operation of the herein described machine, a horizontal tier of 20 rollers, each 30 inches in diameter and 8 feet long, and having 9 upper and 10 lower harvesting points, was supplied with a uniformly applied coating of a 25 per cent solution of polystyrene in isopropyl benzene. The rollers were rotated, adjacent ones turning in opposite directions, at the rate of about R. P. M., i. e., 118 surface feet per minute. Drawn fibers were delivered at the various harvesting points to pairs of carrier tapes 85 (Fig. 4) disposed in the positions occupied by chains 54 in Figs. 1, 2, 3 and 5, and moving at a linear rate of 60 feet per minute. The fibers were continuously severed from the rollers and were conveyed by the tapes and transferred to an accumulator reel 51, ten feet in circumference, which revolved continuously at a rate of approximately 7 R. P. M. In the course of 10 minutes. a batt about A inch thick and weighing about 9 ounces was accumulated on each of the harvester reels. The fibers individually varied from about 3 microns in diameter to submicroscopic size in the order of 0.02 micron. The freshly harvested batts contained from3 to 8 per cent residual solventan amount which can be reduced by further drying but which is insufllcient to cause the fibers to adhere to one another.

The machine is, of course, adapted to operdown at numerous points.

Other modes of applying the principle of my invention may be employed instead of'the ones explained, change being made as regards the mechanism herein disclosed, provided the means stated by'any of the following claims, or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In a machine for making fine fibers, the combination of a plurality of smooth cylindrical rollers disposed in face-to-face relation, tension means to force the rollers together and to form pressure zones between successive rollers, means for driving adjacent rollers in opposite directions; a feeding device for spreading a thin layer of viscid fiber-forming adherent liquid over the converging surfaces of the rollers; an endless flexible moving carrier disposed in the space between the diverging faces of pairs of the rollers, adapted to engage and collect the fibers drawn between such diverging faces; and means to remove the fibers from said carrier.

2. In a machine for making fine fibers, the combination of a plurality of smooth cylindrical rollers disposed in face-to-face relation, tension means to force the rollers together and to form pressure zones between successive rollers, means for driving adjacent rollers in opposite directions; a feeding device for spreading a thin layer of viscid fiber-forming adherent liquid over the converging surfaces of the rollers; an endless fiexible moving carrier disposed in the space beation with fiber-forming liquids and at speeds other thanthose suggested in the foregoing example. Further, the machine may comprise as few as two rollers and correspondingly may have only one harvesting point, or it may have 100 tween the diverging faces of pairs of the rollers, adapted to engage and collect the fibers drawn between such diverging faces, and a reel adapted to engage the fibers on said carrier to remove the same therefrom.

3. In a machine for making fine fibers, the combination of a plurality of smooth cylindrical rollers disposed in face-to-face relation, tension means to force the rollers together and to form pressure zones between successive rollers, means for driving adjacent rollers in opposite directions; a feeding device for spreading a thin layer of viscid fiber-forming adherent liquid over the com verging upper surfaces of pairs of the rollers, comprising a source of such liquid, a header to receive the liquid, disposed transversely of the rollers and movable longitudinally thereover, delivery tubes dependent from the header to deposit liquid on said converging surfaces, and a doctor blade disposed between the converging roller surfaces to control the amount of liquid admitted to the pressure zone; an endless fiexible moving carrier disposed in the space between the diverging faces of pairs of the rollers, adapted to engage and collect the fibers drawn between such diverging faces; and means to remove the fibers from said carrier.

4. In a machine for making fine fibers, the combination of a plurality of smooth cylindrical rollers disposed in face-to-face relation, tension means to force the rollers together and to form pressure zones between successive rollers, means for driving adjacent rollers in opposite directions; a feeding device for spreading a thin layer of viscid fiber-forming adherent liquid over the converging upper surfaces of pairs of the rollers, comprising individual feed-boxes mounted over and held snugly against each of said converging upper surfaces and movable from end to end thereof continuously while the rollers are in motion; an endless flexible moving carrier disposed in the space between the diverging faces of pairs of the rollers, adapted to engage and collect the nbers drawn between such diverging faces: and

means to remove the fibers from said carrier.

5. The apparatus claimed in claim 1, wherein the endless flexible moving carrier is a pair of parallel chains, part of the locus of which passes longitudinally of the rollers and in proximity thereto so as to intercept fibers drawn between thedlverging surfaces, spaced apart a distance slightly less than the diameter of the rollers.

6. The apparatus claimed-in claim 1, wherein 10 N the endless flexible moving carrier is a pair of parallel metal tapes, part of the locusrof which passes longitudinally of the rollers and in proximity thereto so as to intercept fibers drawn between the diverging surfaces, spaced apart'a dis- 15- 8 tance slightly less than the diameter of the rollers.,

ALDEN W. HANSON. REFERENCES crrnn The following references are of record in the flle of this patent:

UNI'IED STATES PATENTS 

